Re: [PATCH V4 01/27] kfifo: add kfifo_alloc_node() helper for NUMA awareness

Caleb Sander Mateos
2025-11-29T19:12:55Z

On Thu, Nov 20, 2025 at 5:59 PM Ming Lei <ming.lei@redhat.com> wrote:
>
> Add __kfifo_alloc_node() by refactoring and reusing __kfifo_alloc(),
> and define kfifo_alloc_node() macro to support NUMA-aware memory
> allocation.
>
> The new __kfifo_alloc_node() function accepts a NUMA node parameter
> and uses kmalloc_array_node() instead of kmalloc_array() for
> node-specific allocation. The existing __kfifo_alloc() now calls
> __kfifo_alloc_node() with NUMA_NO_NODE to maintain backward
> compatibility.
>
> This enables users to allocate kfifo buffers on specific NUMA nodes,
> which is important for performance in NUMA systems where the kfifo
> will be primarily accessed by threads running on specific nodes.
>
> Cc: Stefani Seibold <stefani@seibold.net>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
> include/linux/kfifo.h | 34 ++++++++++++++++++++++++++++++++--
> lib/kfifo.c | 8 ++++----
> 2 files changed, 36 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h
> index fd743d4c4b4b..8b81ac74829c 100644
> --- a/include/linux/kfifo.h
> +++ b/include/linux/kfifo.h
> @@ -369,6 +369,30 @@ __kfifo_int_must_check_helper( \
> }) \
> )
>
> +/**
> + * kfifo_alloc_node - dynamically allocates a new fifo buffer on a NUMA node
> + * @fifo: pointer to the fifo
> + * @size: the number of elements in the fifo, this must be a power of 2
> + * @gfp_mask: get_free_pages mask, passed to kmalloc()
> + * @node: NUMA node to allocate memory on
> + *
> + * This macro dynamically allocates a new fifo buffer with NUMA node awareness.
> + *
> + * The number of elements will be rounded-up to a power of 2.
> + * The fifo will be release with kfifo_free().
> + * Return 0 if no error, otherwise an error code.
> + */
> +#define kfifo_alloc_node(fifo, size, gfp_mask, node) \
> +__kfifo_int_must_check_helper( \
> +({ \
> + typeof((fifo) + 1) __tmp = (fifo); \
> + struct __kfifo *__kfifo = &__tmp->kfifo; \
> + __is_kfifo_ptr(__tmp) ? \
> + __kfifo_alloc_node(__kfifo, size, sizeof(*__tmp->type), gfp_mask, node) : \
> + -EINVAL; \
> +}) \
> +)

Looks like we could avoid some code duplication by defining
kfifo_alloc(fifo, size, gfp_mask) as kfifo_alloc_node(fifo, size,
gfp_mask, NUMA_NO_NODE). Otherwise, this looks good to me.

Best,
Caleb

> +
> /**
> * kfifo_free - frees the fifo
> * @fifo: the fifo to be freed
> @@ -899,8 +923,14 @@ __kfifo_uint_must_check_helper( \
> )
>
>
> -extern int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
> - size_t esize, gfp_t gfp_mask);
> +extern int __kfifo_alloc_node(struct __kfifo *fifo, unsigned int size,
> + size_t esize, gfp_t gfp_mask, int node);
> +
> +static inline int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
> + size_t esize, gfp_t gfp_mask)
> +{
> + return __kfifo_alloc_node(fifo, size, esize, gfp_mask, NUMA_NO_NODE);
> +}
>
> extern void __kfifo_free(struct __kfifo *fifo);
>
> diff --git a/lib/kfifo.c b/lib/kfifo.c
> index a8b2eed90599..525e66f8294c 100644
> --- a/lib/kfifo.c
> +++ b/lib/kfifo.c
> @@ -22,8 +22,8 @@ static inline unsigned int kfifo_unused(struct __kfifo *fifo)
> return (fifo->mask + 1) - (fifo->in - fifo->out);
> }
>
> -int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
> - size_t esize, gfp_t gfp_mask)
> +int __kfifo_alloc_node(struct __kfifo *fifo, unsigned int size,
> + size_t esize, gfp_t gfp_mask, int node)
> {
> /*
> * round up to the next power of 2, since our 'let the indices
> @@ -41,7 +41,7 @@ int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
> return -EINVAL;
> }
>
> - fifo->data = kmalloc_array(esize, size, gfp_mask);
> + fifo->data = kmalloc_array_node(esize, size, gfp_mask, node);
>
> if (!fifo->data) {
> fifo->mask = 0;
> @@ -51,7 +51,7 @@ int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
>
> return 0;
> }
> -EXPORT_SYMBOL(__kfifo_alloc);
> +EXPORT_SYMBOL(__kfifo_alloc_node);
>
> void __kfifo_free(struct __kfifo *fifo)
> {
> --
> 2.47.0
>